CFM out of pressurized vessel
CFM out of pressurized vessel
(OP)
I am trying to calculate the volume flow rate out of a pressurized vessel. The pressure in the tank is being held constant at 120 psi by a compressor and contains air. There is a 1 inch outlet on it. I have calculated the mass flow rate by assuming choked flow and using:
Q = C A sqrt (g k rho P ((2/k+1)^(k+1/k-1)))
where
C is discharge coefficient (assume about 0.75)
A is outlet area
g is gravity
k is ratio of specific heats (1.4)
rho is density
P is pressure in the tank (120 psi)
I got a mass flow rate of 0.549 lb/s leaving the tank. How do I convert this to CFM? Simply dividing by density? How do I know the density at the outlet?
Q = C A sqrt (g k rho P ((2/k+1)^(k+1/k-1)))
where
C is discharge coefficient (assume about 0.75)
A is outlet area
g is gravity
k is ratio of specific heats (1.4)
rho is density
P is pressure in the tank (120 psi)
I got a mass flow rate of 0.549 lb/s leaving the tank. How do I convert this to CFM? Simply dividing by density? How do I know the density at the outlet?





RE: CFM out of pressurized vessel
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: CFM out of pressurized vessel
RE: CFM out of pressurized vessel
You've mistaken seconds for minutes - 0.549 lbs/ SEC divided by 0.0749 = 7.3 CFS = 438 CFM at whatever pressure 0.0749 relates to so if this is standard then it is 438 scfm. Sounds a bit more like it for a 1" hole with 120psi behind it...
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: CFM out of pressurized vessel
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: CFM out of pressurized vessel